If this turns into a full-scale war or a civil war breaks out, we are looking at 1 million Iranian deaths conservatively speaking. Just look at happened at every single foreign intervention in the region - Iraq, Syria, Libya, Sudan, Somalia. How does a million dead Iranians help them? How does it help the Americans, and the world if oil infrastructures or shipping lanes are targeted ? How does it help the region or Europe when millions of refugees flood out, and armouries are broken open and weapons and insurgents flood the region (like it did with Iraq and Libya)? It helps Israel greatly though, since they take out their arch nemesis, their conventional military and the nuclear program. And they think can shield themselves from the chaos they create around them.